> Only onto a 2300 (which will use ANY Duo screen). The 280 screen is an > active screen vs. passive on the 230/250 series. >
The 250 actually has an active matrix screen, but the cable connector is not compatible with the 280 or 280c. It is compatible with the passive matrix 230 though. An LCD display is basically composed of two sheets of polarized plastic or glass. The top sheet is polarized 90 degrees different than the bottom. That is, the top could be horizontal and the bottom vertical. Light cannot pass through these two sheets of oppositely polarized glass. The light source is polarized in all directions randomly, but the only light which can pass through the first sheet is that which is polarized in its horiz. direction. This light would come to a screeching halt when it hits the second sheet of glass because it is polarized in the vertical direction. Here is where the liquid crystal material, which is essentially sandwiched in between the two sheets, comes into play. When no electrical energy is passing through a pixel of liquid crystal, the crystal is a twisted noodle-like affair. Horizontal light gets twisted around such that it can pass through the next layer (vertical) of glass. But, put an electrical charge to the liquid and it straightens out. Now it won't twist the light around. The horizontally polarized light remains horiz and hits the vertical glass and it goes no further. This appears as a black spot (pixel). The reason that the black and white (grayscale) LCDs work in the sunlight or ambient light is this. Ambient light can shine right through the clear polarized sheets, with the twisted crystals, to a reflective surface on the back of the display, and reflect back out to your eyes. But, when a pixel is turned on, a black spot appears. But here is the rub with color. Instead of two essentially clear sheets of glass with liquid crystal pixels sandwiched in between, the color display is made of two sheets of glass, each one being a matrix of colored glass pixels. Think of stained glass windows. There is no "clear" glass to let white light through. There are only many little red, green and blue colored windows. A red window only lets red light (sunlight) through. Then this red sunlight hits the reflective back surface and scatters about, and reflects back out. But in so doing, it tries to go through red windows (good) and green windows (bad) and blue windows (also bad). Very little of the sunlight gets back out. There are new "sunlight readable" color displays that work by essentially placing the reflective backing material extremely close to the polarized sheets of glass. That way white light going in through a red window can only return through that very same window. This type of display does not have a "backlight", but rather it has a "frontlight" for use when the ambient light is insufficient. All the above is rather simplified but it is the basic principle in a nutshell, written from the ramblings of a nut! Actually, I find the principle of the LCD fascinating and sometimes I just need to talk about it. Maybe an LCD 12 step program? whatever. Greg ---------- Duo/2400 List, The friendliest place on the Net! A listserv for users and fans of Mac subportables. FAQ at <http://www.themacintoshguy.com/lists/DuoListFAQ.shtml> Be sure to visit Mac2400! <http://www.sineware.com/mac2400> To unsubscribe, E-mail to: <[EMAIL PROTECTED]> To switch to the DIGEST mode, E-mail to <[EMAIL PROTECTED]> Need help from a real person? Try. <[EMAIL PROTECTED]> ---------- Dr. Bott | 10/100 Ethernet for your 2400 is finally here! MPC-100 | <http://www.drbott.com/prod/mpc100.html> RoadTools $30 PodiumPad available at Apple retail stores, $20 Traveler CoolPad at Staples. Both in white for iBooks at <http://roadtools.com> Midwest Mac Parts ][ <http://www.midwestmac.com> After-market parts for Macs. ][ 888-356-1104 ][ MacResQ Specials: LaCie SCSI CDR From $99! PowerBook 3400/200 Only $879! Norton AntiVirus 6 Only $19! We Stock PARTS! <http://www.macresq.com>
